Driving system for centrifugals or the like



3 Sheets-Sheet 1 .INVENTOR. JOSEPH HEPTP/CH Y I I MM 11m ,4 T TOQNE Y5 May 11, 1948. J HERTRICH DRIVING SYSTEM FOR CENTHIFUGALS QR THE LIKE Filed March 17. 1942 May 11, 1948. J. HERTRICH DRIVING SYSTEM FOR CENTRIFUGALS OR THE LIKE Filed March 17, 1942 3 Sheets-Shqet 2 .H y .C R/ mm 0 R m5 1 P 6 x f m 2 4 r0 6 r0 5 8 7 1 n (W 5 flu\ on 5 5 H W ML W 5 2 M V 5 May 11, 194 8.

J. HERTRICH 2,441Q356 DRIVING SYSTEM FOR QENTRIFUGALS OR THE LIKE Filed March 17, 1942 3 Sheets-Sheet 3 INVENTOR. JOSEPH Ht''TP/CH 14 T TORNEXS Patented May 11, 1948 DRIVING SYSTEM FOR CENTRIFUGALS OR THE LIKE Joseph Hertrlch, Hamilton, Ohio, assignor to The .rWestern States Machine Company, Hamilton,

Ohio, a corporation of Utah Application March 17, 1942, Serial No. 435,023 is Claims. (Cl. sos4) This invention relates to new and useful improvements in driving systems for sugar centrifugals and other heavy dutymachines which operate in a discontinuous or cyclical manner.

By critical standards, no conventional driving system for sugar centrifugals can be considered quite satisfactory. ,This is particularly true of high speed centrifugals driven by individual electric motors. Where the motors are directly connected they have had to be constructed especially to withstand overloads and avoid overheating during accelerations and discharging operations; yet the acceleration of such centrifugals is still not uniform, and objectionable power peaks are encountered in their operation. Where motors work through mechanical slip clutches, overheating and wearing of the clutch elements are constant sources of trouble, expense and nonuniform operating conditions. Where motors and hydraulic couplings, or clutches, have been used it has been impractical to avoid overloads on the motor and overheating of the coupling and still maintain an efllcient and uniform power transmission through the coupling under the varying conditions of slip between the driving.

and driven members. I

It is desirable that sugar centrifugals accelerate at a uniform rate, and also that the acceleration rate be selected to suit the purging qualities of the particular material under treatment and be kept exactly the same for each and every cycle of treatment of the same material. But no motor-driven centrifugal heretofore used has enabled these results.

Furthermore, with the use of prior centrifugal driving systems it has not been possible, though it is desirable, to maintain a common and uniform control over the accelerating characteristics of several different machines.

It is therefore an object of the present invention to provide a driving system for centrifugal machines, and for other machines that present 7 similar problems, which eliminates many of the above mentioned shortcomings of known centrifugal driving systems. More particularly, I

propose to provide such a driving system which.

will maintain a definite maximum torque under all conditions of excessive torque demand, hence throughout the acceleration period in every cycle of operation of the machine, thus preventing overloading of the driving member, reducing power peaks and securing a regular and uniform rate of acceleration for the machine. I also propose to provide such a system which will enable the accelerating torque of the machine to be selected and set at any of a wide range of values, thereby enabling the same machines to be used withdii'ierent acceleration rates for the most eillcient treatment of different types of material.

Another object of my invention is to provide a new driving system for centrifugal machines or the like which automatically limits the torque transmission to a* predetermined value during operating periods of excessive torque demand, by allowing the necessary slip between the driving and driven members of the machine, yet which automatically minimizes the slip and so gives the most efficient power transmission within the capacity of the system whenever the torque demand is below the limiting value, as when-the machine has been accelerated to its full running speed.

A further objectof my invention is to provide a driving system for sugar centrifugals or the like which places two or more independently operable machines under a common torque control and makes it possible to keep the several machines operating with identical accelerating characteristics.

Another object of my invention is to provide an improved driving and torque control system for a motor driven centrifugal machine or the like which makes it practical to use an electric motor of standard construction for heavy duty machine operations, eliminating the need for more expensive motors constructed especially to withstand excessive overloads and avoid overheating. Still another object is to provide such a system which is quite practical and economical to construct, install and use.

Other objects of my invention are to provide simple means for holding the torque transmitted from a prime mover through a hydraulic coupling constant over the whole speed range of the system during acceleration; to provide simple means for changing the torque rating of a motor driving system which drives through a hydraulic coupling without affecting the driving characteristics of the motor; to provide means for controlling the oil flow to the hydraulic coupling by I directly measuring the torque exerted by a motor which drives the coupling, and in instantaneous response to the motor torque; and to provide a torque control means which acts fast enough to maintain a smooth power curve and prevent hunting. 1

According to preferred embodiments of this invention, a hydraulic clutch or coupling is employed for transmitting a limited but variable torque between a driving motor and the driven machine; and a variable control means is provided which responds automatically to the torque being delivered at any moment by the motor and which controls the torque transmitted to the machine through the coupling, hence the torque of the motor, by varying the quantity of liquid in the coupling.

To prevent overheating of the coupling and also secure a convenient torque control, oil is circulated through the coupling during its operation, and the torque varied by varying the rate of oil circulation. For example, the oil supply system for the coupling may be provided with a variable control valve for regulating the rate of oil inflow, and the coupling itself may have an oil discharge means, such as one or more bleeder holes, through which oil may escape at a more or less constant rate. In such cases, a change in the setting oi! the control valve will change the oil inflow rate and in that way in crease or reduce the quantity of oil in the coupling, which of course will increase or reduce the torque of the coupling for any given arrangement and degree of slip between the coupling members. With a suitable rate of discharge the oil will prevent the coupling becoming overheated, and the oil that is discharged may be cooled and recirculated through the corn trol valve and back into the coupling.

Such a control valve is made operative to control the torque of the coupling, according to my invention, by utilizing the fact that the stator of the driving motor is aimays subject to a torque reaction that is equal to the torque of the motor, though oppositely directed. The motor frame holding the stator and likewise the base plate and other structure which support the motor are subject to the same torque reaction. A control means quickly reactive to the torque of the driving motor may be completed pursuant hereto by providing for a limited shifting or turning movement of the stator or the motor frame, or even of structure to which the motor is fastened, if desired; by associating the shiftable motor frame with the variable control valve in the oil supply system of the hydraulic coupling, so that movement of the motor in reaction to its own torque may cause a reduction in the torque of the coupling; and by opposing such movement of the motor and control valve by spring means or fluid under pressure. The spring means or fluid pressure then urges the control valve and the motor frame toward a position to increase the quantity of oil in the coupling, and the torque reaction of the motor acts in the opposite direction and urges the motor frame and control valve toward a position to reduce the quantity of oil in the coupling. The torque that can be applied by the driving system therefore becomes a direct function of the spring or fluid pressure, and the value of that torque may be changed by changing the spring or its compression, or by changing the fluid pressure.

Accordingly, the spring or fluid pressure is selected so as to provide that desired accelerating torque for the machine, within the capacity of the driving motor and the hydraulic coupling, which results in a uniform selected acceleration and at the same time protects the motor against overloads or overheating during acceleration and other periods of excessive torque demand. On the other hand, when the inertla or drag of the machine falls below the predetermined torque limit, such as when the machine has completed its acceleration, the hydraulic coupling will receive more oil and deliver its maximum power with a minimum loss of energy through slippage and heat.

A torque control system for a group of machines is obtained according to this invention by providing each machine with a system of the type described, in which fluid pressure determines the limiting torque, and by supplying the fluid pressure for every machine of the group from a common source, so that the accelerating characteristics of each machine are fixed by a force which is the same for every other machine. in a particularly desirable embodiment, hydraulic pressure is used for this purpose and is supplied from an oil circulation system that also is used to supply 011 for the hydraulic couplings of the several machines.

The foregoing and other objects, features and advantages of my invention will become more apparent from the following description of illustrative embodiments thereof, when considered in connection with the accompanying drawings forming a part hereof. It will be understood, however, that this invention may be applied in various ways, without limitation to the features of these illustrative embodiments except as may be required by the appended claims. In the drawings,

Figure l is a front elevation, partly in section and partly diagrammatic, of a suspended gyratory centrifugal machine embodying this invention;

Figure 2 is a horizontal section, substantially along line 2-2 of Figure 1;

'Eigure 3 is an enlarged vertical section showing parts of the hydraulic coupling oi the machine in Figure 1;

Figure 4 is a horizontal section, substantially along line fl4 of Figure 1;

Figure 5 is a fragmentary vertical section, substantially along line 5-li of Figure 4;

Figure 6 is a vertical section, substantially along line 8-45 of Figure 4;

Figure 7 is a diagrammatic illustration of another embodiment of the invention;

Figure 8 is a diagrammatic illustration of a third embodiment of the invention, wherein it is applied for the control of a group of centrifugal machines; and

- Figure 9 is a vertical section through a liquid control valve such as may be used in the embodiment of Figure 8.

In Figure 1 01 the drawings I have illustrated a preferred motor-driven centrifugal arrangement intended for use in the manufacture of sugar. The machine includes the usual perforate basket l0 located inside a surrounding casing i2 and suspended by a spindle H from a syratory centrifugal head it. A brake drum I1 is secured for rotation with the spindle and adapted to be engaged by friction brake bands Ila in any suitable manner. The head it contains bearings and a, suitable ball and socket or universal Joint (not shown) which provides for the requisite gyratory or swinging movement of the basket and spindle under unbalanced loads during operation of the machine. The weight of the basket and spindle assembly is sustained by a stationary motor shaft to a positive driving connection witha part 22 oi a flexible coupling (not iully shown) which in turn positively connects the shait 28 through the head II for rotation with the centriiugal spindle l4. This particular arrangement is not claimed as a ieature oi the present invention, but is claimed in my copending application, Serial No. 874,668, filed January 18, 1941; now United States Patent 2,380,595. It obviously may be varied in many respects within the purview oi the invention hereinclaimed, such as by using a solid shait motor and disposing the hydraulic coupling between the motor and the centriiugal' head, or otherwise.

It will be understood that when the driving motor is energized and the coupling 20 contains 011 between its impeller and runner members the motor will apply a torque through the hydraulic coupling to the driven shaft 28 and the centriiugal. The coupling has an oil supply system connected with an inlet pipe 36 that leads oil axially 6 I valve itselicontains a cylindrical plunger Cl which has two seats 82 and 44 controlling the admission oi oil to pipes 44 and II, respectively. A compression spring ll bears at one end against an end piece 04 oi the valve body and at its other end against the end oi plunger ll, so tending to hold the plunger against seat 04 and to keep seat 22 open ior iull flow oi oil through a duct I0 and line '4 to the inlet 2| oi the hydraulic coupling. At its forward end the plunger I has a stem I2 that extends through and is sealed to a flexible into the rotary coupling housing 28. An oiitake pipe 4il-takes oil iromthe bottom of a stationary oil collector 42 that surrounds'the coupling and is mounted on the upper end shield of the motor irame 22. The peripheral '-'wall of housing 28 is provided with several small bleeder holes 44 which allow a continuous discharge oi oil during opera-' tion oi the coupling. The bleeder holes 44 are made at least large enough to keep oil flowing from the coupling under centriiugal iorce at a rate suflicient to prevent overheating oi the oil.

By cooling this heated oil and recirculating it to the coupling the excess heat generated durin acceleration oi the centrliugal or other periods of high torque is readily disposed oi, and the coupling is kept operating at a. temperature conducive to eiiicient power transmission. For this purpose the oil from collector 42 may pass through pipe 40 to an oil tank 46, from which it may be withdrawn by a pump 48 and passed through an oil cooler 42 en route back to pipe 26 and the coupling.

It will be understood that the torque of the hydraulic coupling and the load on the motor, at any certain basket speed corresponding'to a certain degree oi slip between the impeller 32 and the runner 24, will vary with the quantity of oil inside the coupling, and also that the quantity oi oil inside the coupling may be controlled by varying the rate of oil supply through pipe 38. The quantity of the liquid in the coupling at any given speed or degree of slip determines the accelerating power or torque transmitted to the basket of the machine and is controlled pursuant hereto so as to hold the acceleration characteristics constant in each cycle oi operation, yet permit variation oi the acceleration rate, at will, to suit theneeds oi the material being treated.

This control over the quantity at liquid in the coupling and the torque transmission of the coupling is eiiected as iollows: A three-way control valve 50 is provided at some convenient location adjacent the motor irame 22, such as by mounting it on the base plate 20. (See Figures 1, 2, 4 and 6.) Oil irom cooler in enters this valve through a pipe 52. A second pipe 54 leads from the valve body II to a connection with the coupling inlet pipe 26. A third pipe 56. leads irom the valve body back to the oil tank 48. The

' mitted to arm 80, set screw 22 and stem 12 oi the diaphragm 14 held across that end of the valve body by means oi an end piece 18. A passage II in the plunger equalizes the hydraulic pressure on the plunger and allows oil to pass irom the plunger into a duct 18 and thence into pipe it whenever the plunger is moved away irom seat 44.

As shown more particularly in Figures 2 and 4, an arm 22 is secured to the lower end shield of the motor irame 22 to extend radially to a position opposite the end oi stem I2, and a set screw s2 is threaded in arm so as to abut against the end oi stem 12. The motor irame itseli is mounted ior limited angular movement in a manner hereaiter to be described. It will be apparent that when the motor irame moves to any appreciable extent'in a counterclockwise direction, as seen in Figure 4, such movement will be transplunger ill and will shift the plunger against the force oi spring 86 in a direction tending to close valve seat 62 and open valve seat 84. To the extent oi this movement the flow oi oilirom the valve into the hydraulic coupling will be restricted, and the excess oil will be by-passed over seat 84 through pipe 58 to the oil tank 46. It also will be apparent that the spring 08 prevents such movement oi the motor irame until the opposing force exerted by the arm 80 becomes large enough to overcome the ionce oi the spring.

The motor irame is mounted for limited angular movement in reaction to the torque oi the motor as iollows: The adaptor plate 22b is made iast to the motor base plate 20 by means oibolts 84. The motor is held down on the adaptor plate 22b by means of bolts 8' and compression springs 80. These bolts extend through bolt holes 82 in the flanges 22a, as seen in Figure 4. The holes ll are enlarged slightly say, about one-eighth oi an inch, to allow limited angular movement of the frame. To facilitate such movement, the adaptor plate 22!) preierably is iormed withan open circular groove 82, and a circular row of ball bearings 94 is disposed in this groove to sustain the thrust oi the motor while reducing the frictional resistance to its angular motion.

As further shown in Figures 1, 2 and 4, a second radial arm 80a may be provided on the motor irame 22 diametrically opposite to arm 80 and arranged for co-action with a second valve body "it having a plunger 80a and a compression spring 66a therein. This structure balances the a force opposing angular movement oi the motor centrifugal. the torque of the motor being in a clockwise direction as viewed in Figure 4. The centrifugal has a heavy inertia to be overcome by the driving system, so that the motor torque immediately attains a value such that the correspending torque reaction on the stator 24 and the motor frame 22 becomes suflicient to shift the frame counterclockwise against the force of springs 88 and 86a. Meanwhile oil is continuously discharged from the coupling through the bleeder holes 44, and when this shifting movement of tire motor frame and control valve takes place there is an immediate reduction in the rate of oil flow over valve seat 82 to the coupling, which directly causes a reduction in the quantity of liquid in the coupling and hence a reduction in the torque of the coupling and the drag on the motor. When, however, this torque or drag falls below the value necessary to compress the springs 88 and 88a, the springs cause a shifting of the valve plunger and motorframe 22 in a clockwise direction, so increasing the inflow of oil to the coupling. Accordingly, an equilibrium condition is maintained which prevents the torque or load on the motor exceeding the predetermined value set by the control springs, and as long as the inertia of the machine exceeds this value a substantially constant accelerating torque will be applied to the machine. As soon, however, as the centrifugal reaches its full running speed, or whenever the reduced slip between the impeller and runner of the coupling lowers the coupling torque below the torque established by the spring pressure, the springs 86 and 88a shift the control valve to give the maximum oil flow to the coupling, so that the coupling under those conditions becomes substantially full of oil and operates at its maximum power transmission efficiency.

Because of the very small travel of the control valve, and because it acts under direct application of the full power of the machine and exerts relatively a very small frictional resistance to that power, the action of the control is almost instantaneous, and there is no lag or resultant hunting in the reaching of equilibrium conditions.

According to a second embodiment of the invention, as illustrated in Figure '1, the general arrangement and combination of parts is similar to the first embodiment, but fluid pressure is used inplace of spring pressure to control the accelerating torque of the'machine. In this embodiment the oil-take pipe 40 from the oil collector 42 leads to an oil tank I46, and a pump I48 draws oil from the tank and passes it through a cooler I48 to a control valve I58. The body of this valve houses a plunger I60 having two enlarged portions I'8I and I62 for closing or opening respective ducts I68 and I64. An 011 line I65 leads from the cooler into a space IE6 at one end of the valve body, where the oil presses against an end of the plunger I80. The other end I61 of the plunger abuts against a set screw 82 on a radial arm 80 which is secured to the movable motor frame as in the embodiment first described. Duct I64 of the valve body connects with an oil line I88 leading to the coupling inlet 38. Duct I63 connects with an oil line I10 leading back to the tank I48. A pipe I12 is connected with the pressure line I85 to carry oil from the cooler I49 into space I5I of the valve body, but this pipe has a pressure relief valve I14 in it to ensure a definite predetermined pressure on the oil in line I48. The relief valve I14, for example. may be set to be released at a pressure of thirty pounds per square inch. A pipelli extends from pipe I12 back to the oil tank I48 and has a pressure relief valve I18 in it to ensure a substantially constant pressure on the oil entering the valve body. The pressure maintained by valve I18. for example, may be aboutten to twenty pounds per square inch.

In the operation of this embodiment, the oil pump I48 feeds oil to the pressure line I88 and through the relief valve I14 in line I12 under pressure of, e. g., thirty pounds per square inch. This pressure forces the plunger I80 in a direc tion giving a full oil supply through duct I84, line I88 and inlet 28 to the hydraulic coupling. On the other hand, when the torque reaction on the motor frame 221s suflicient to overcome the pressure of thirty pounds per square inch exerted on the end of plunger I80, the plunger is moved in a right-hand direction as seen in Figure 7, with the result'of reducing the flow of oil to the coupling and by-passing the excess oil through duct I82 and line I18 back to the tank I48. The torque of the driving system during acceleration therefore will be maintained substantially constant at a value established by the setting of relief valve I14, and the torque may be varied by changing this value or its setting.

Figure 8 of the drawings illustrates diagrammatically a third embodiment in which the invention is applied to maintain a uniform control over the torque characteristics of a group of centrifugal machines. Four machines-a, b, c and d-are indicated in the drawings. They may be constructed and arranged in substantially the same manner as the machines already described. The oil inlet 28 for the hydraulic coupling of each machine receives oil through a control valve 288, which has a line 288 leading to the coupling inlet, an oil supply line.212, and a pressure line 285. The off-take pipe 48 from the oil collector 42 of each machine is connected with a common header 248 which carries the oil discharged from the several couplings back to a common oil tank 248.

In this case the body of each control valve 250 houses a plunger 280 one end of which is subject to oIl pressure admitted through line 285, and the other end of which is associated with an arm 80 on the motor frame 22 in substantially the same manner as already described with respect to previous embodiments. A duct 264 in each valve body communicates with the oil supply line 212 and is adapted to be closed-01f or opened. to regulate the flow through line 288'to the coupling, by the action of an enlargement 282 on plunger 260. The several oil supply lines 212 stem from a common header 288. The several pressure lines 265 stem from a common header 282. A pump 248 forces oil from tank 246 through a cooler 249 and a pipe 28I into the pressure header 282. A pipe 284 connects at one end with the oil supply header 288 and has two branches 288 and 288. Branch 288 is connected with the pressure pipe 28I through a pressure relief valve 214. Branch 288 extends back to the tank 248 through a pressure relief valve 218.

The setting of valve 214 therefore determines the torque-controlling pressure for thefour machines and the setting of valve 218 determines the pressure of the oil supply for the hydraulic couplings of the four machines. It will be-apparent that each machine of the group remains subject to operation independently of every other machine in the customary manner for sugar centrifugals, but also that the torque or accelerating characteristics of all four machines may be set at any desired value and maintained uniform in each and every operating cycle.

While I have illustrated and described several preferred embodiments of my invention, the invention is not limited to such embodiments but may be utilized to advantage in many other ways. I therefore desire that it be accorded a scope fully commensurate with its novel contributions to the art, which are intended to be defined by the apv pended claims.

I claim: a 1. In combination with a heavy-duty machine 'to decrease the liquid supply under a force always proportionateto the motor torque.

6. In a machine having a rotary driven shaft,

and a motor connected therewith for rotating the same, 9. hydraulic coupling for transmitting that is reactive to its torque for limited angular 1 movement, and means connecting said part with comprising a driven shaft and rotary driving means including a motor and a hydraulic coupling, means connected with said motor and shiftable in one direction by the torque reaction of said motor, yieldable means to exert continuously a predetermined force tending to move said shiftable means in another direction in opposition to such torque reaction, and means operated by said shiftable means for varying and controlling the volume of fluid in said coupling.

2. In combination. a rotary machine having a driven shaft, a 'motor having a rotary driving shaft, a hydraulic coupling for transmittin power between the driving and driven shafts, and means continually subject to the torque reaction of the motor and shiftable in direct response thereto for limiting to a predetermined value the torque transmission of the coupling.

3. In combination with a heavy-duty machine comprising a rotary driven shaft, a rotary driving motor and a hydraulic coupling to transmit power from the motor shaft to the driven shaft, means for supplying liquid-into said coupling, means for discharging liquid from said coupling,-a control valve for varying the rate of liquid supply, means to apply continuously to said valve a predetermined force urging said valve toward open position, and means connected to said valve and to the motor and directly reactive to the torque of said motor to urge said valve toward closed position with a force always proportionate to said torque. l

4. In combination with a heavy-duty machine comprising a rotary driven shaft, 9, driving means having a rotary driving shaft and a hydraulic coupling to transmit torque between said shafts, means for circulating liquid into and out of said coupling including movable valve means outside the coupling for controlling the flow of liquid into the coupling, means urging said valve means yieldably toward a position to increase the quantity of liquid in the coupling, and means operated by a force equal at all times to the torque of said driving means for counteracting said last-recited means and moving said valve means toward a position to reduce the quantity of liquid in the coupling.

5. In combination with a machine comprising a rotary driven shaft, driving means havin a rotary driving shaft, and a hydraulic coupling to connect said shafts, means for continuously sup plying liquid into said coupling, means in said coupling for continuously discharging liquid therefrom, movable means for varying the rate of liquid supply, means for continuously urging said movable means under a predetermined. force toward a position to increase the liquid supply, and means connected to said driving means and directly responsive to the torque reaction thereof for urging said movable means toward a position said control valve and responsive to the torque reaction of the motor for urging the valve toward closed position against the resistance imposed by said pressure applying means.

7. In combination with a machine having a rotary driving motor, a rotary driven shaft and a hydraulic coupling to transmit power from the motor to the driven shaft, means mounting the motor frame for limited turning movement in reaction to the motor torque, an oil supply line leading to said coupling. a control valve in said line to vary the oil inflow to the coupling, means in the coupling for continuously discharging oil therefrom, means operated by such turning movement of said motor frame for moving said control valve toward a closed position, fluid-pressure-responsive means for opposing such turning movement of the frame and urging said control valve toward an open position, and means for applying a predetermined fluid pressure to said fluid-'pressure-responsive means.

8. In combination with a machine having a rotary driving motor, a rotary driven shaft and a hydraulic coupling to transmit power from the motor to the driven shaft, means mounting the motor frame for limited turning movement in reaction to the motor torque, an oil supply line leading to said coupling, a control valve in said line to vary the oil inflow to the coupling, means in the coupling for continuously discharging 'oil therefrom, means operated by such turning movement of said motor frame for moving said control valve toward a closed position, fluidpressure-responsive means for opposing such turning movement of the frame and urging said control valve toward an open position, on oil pressure .line leading to said fluid-pressureresponsive means, means connecting said oil supply line with said pressure line. means for forcing oil under pressure into said pressure line and connecting means, and a pressure relief valve in said connecting means to maintain a predetermined substantially uniform pressure in said pressure line.

9. In combination with a machine having a rotary driving motor, a rotary driven shaft and a hydraulic coupling to transmit power from the motor to the driven shaft, means mounting the motor frame for limited turning movement in reaction to the motor torque, an oil supply line leading to said coupling, a control valve in said line to vary the oil inflow to the coupling, means in the coupling for continuously discharging oil therefrom, means operated by such turning movement of said motor frame for moving said control valve toward a closed position, fluid-pressureresponsive means for opposing such turning movement of the frame and urging said control valve toward an open position, an oil pressure line leading to said fluid-pressure-responsive means, means connecting said oil supply line with said pressure line, an oil supply tank, pump means to force oil from said tank into said pressure line '11 and said connecting means, a pressure relief valve in said connecting meansto maintain a predetermined substantially uniform pressure in said pressure line, an oil return line connecting said supply line with said tank, and a pressure relief valve in saidreturn line to maintain a predetermined pressure in said supply line.

10. In a suspended centrifugal machine, a ver-; tical driven shaft, a stationary motor support, a

vertically mounted rotary driving motor on said support, a hydraulic coupling to couple the motor shaft with said driven shaft, bolts securing the motor frame to said support, enlarged holes for said bolts to permit limited angular movement of said frame relative to said support and means responsive to movements of said frame for varying the torque of said coupling.

11. In combination, a plurality of machines each having a rotary driving motor, a rotary driven shaft, a hydraulic coupling to tralmmit power to the driven shaft from the motor, a motor frame mounted for limited turning movement in reaction to the motor torque, an oil supply line leading into the hydraulic coupling, a control valve in said line to vary the oil inflow to the coupling, means in the coupling for continuously discharging oil therefrom, means operated by such turning movement of said frame for moving said control valve to restrict said oil inflow and iiuid-pressure-responsive means for opposing turning movement of said frame and urging said control valve toward a position for full 011 inflow, an oil supply header common to said supply lines, an oil pressure header having branch lines leading to the respective fluid-pressure-responsive means, means connecting said supply header. with ing said control valve toward a position for full oil inflow, an ofl supply header common to said supply lines, an oil pressure header having branch lines leading to the respective fiuid-pressure-responsive means, means connecting said supply header with said pressure header, an oil tank and pump for forcing oil into said pressure header and said connecting means, a pressure relief valve in said connecting means to maintain a predetermined substantially uniform pressure in said pressure header and branch lines, an oil return line connecting said supply header with said oil tank, and a pressure relief valve in said return line to maintain a predetermined pressure on the oil in said supply header and said supply lines.

13.'In a heavy-duty machine, a vertical rotary driven shaft, a motor support thereabove, an electrlc driving motor, a hydraulic coupling to transmit power from the motor shaft to said driven shaft, means mounting the stator-carrying frame of said motor in vertical position for limited turning movement on said support, said means including a circular series of bearings between the motor frame and the support, an oil supply line I said motor in opposition to said force-exerting said pressure header, an oil tank and pump for i forcing oil into said pressure header and said connecting means, and a pressure relief valve in said connecting means to maintain a predetermined substantially uniform pressure in said pressure header and branch lines.

12. In combination, a plurality of machines each having a rotary driving motor, a rotary driven shaft, a hydraulic coupling to transmit power to the driven shaft from the motor, a motor frame mounted for limited turning move ment in reaction to the motor torque, an oil supply line leading into the hydraulic coupling, a control valve in said line to vary the oil inflow to the coupling, means in the coupling for-continuously discharging oil therefrom, means operated by such turning movement of said frame for moving said control valve to restrict said oil inflow and fluid-pressure-responsive means for o posing turning movement of said frame and urgmeans.

JOSEPH HERTRICH.

REFERENCES one!) i The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 552,521 Field Jan. 7, 1896 1,282,344 Willey Oct. 22, 1918 1,387,149 Fynn Aug. 9, 1921 1,536,915 Olcott May 5, 1925 1,663,513 Howse Mar, 20, 1928 1,768,938 Sinclair July 1, 1930 1,855,032 Sinclair Apr. 19, 1932 2,227,814 Tyler Jan. 7, 1941 2,287,709 Ringman June 23, 1942 2,300,338 Camerota Oct. 27, 1942 2,301,719 Turchan Nov. 12, 1942 FOREIGN PATENTS Number Country Date 541,961 Germany 1932 

